U.S. patent application number 13/216683 was filed with the patent office on 2011-12-15 for flow reduction hood systems.
This patent application is currently assigned to Voyage Medical, Inc.. Invention is credited to David MILLER, Ruey-Feng PEH, Chris A. ROTHE, Vahid SAADAT, Edmund TAM.
Application Number | 20110306833 13/216683 |
Document ID | / |
Family ID | 45099290 |
Filed Date | 2011-12-15 |
United States Patent
Application |
20110306833 |
Kind Code |
A1 |
SAADAT; Vahid ; et
al. |
December 15, 2011 |
FLOW REDUCTION HOOD SYSTEMS
Abstract
Flow reduction hood systems are described which facilitate the
visualization of tissue regions through a clear fluid. Such a
system may include an imaging hood having one or more layers
covering the distal opening and defines one or more apertures which
control the infusion and controlled retention of the clearing fluid
into the hood. In this manner, the amount of clearing fluid may be
limited and the clarity of the imaging of the underlying tissue
through the fluid within the hood may be maintained for relatively
longer periods of time by inhibiting, delaying, or preventing the
infusion of surrounding blood into the viewing field. The aperture
size may be controlled to decrease or increase through selective
inflation of the membrane or other mechanisms.
Inventors: |
SAADAT; Vahid; (Atherton,
CA) ; TAM; Edmund; (Mountain View, CA) ;
ROTHE; Chris A.; (San Mateo, CA) ; MILLER; David;
(Cupertino, CA) ; PEH; Ruey-Feng; (Singapore,
SG) |
Assignee: |
Voyage Medical, Inc.
Redwood City
CA
|
Family ID: |
45099290 |
Appl. No.: |
13/216683 |
Filed: |
August 24, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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12026455 |
Feb 5, 2008 |
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13216683 |
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60888242 |
Feb 5, 2007 |
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Current U.S.
Class: |
600/109 |
Current CPC
Class: |
A61B 1/00165 20130101;
A61B 18/18 20130101; A61B 17/29 20130101; A61B 1/018 20130101; A61B
1/051 20130101; A61B 18/00 20130101; A61B 1/3137 20130101; A61B
1/00147 20130101; A61B 1/015 20130101; A61B 1/32 20130101; A61B
6/503 20130101; A61B 1/0008 20130101; A61B 1/05 20130101; A61B
5/6851 20130101; A61B 1/12 20130101; A61B 1/00089 20130101 |
Class at
Publication: |
600/109 |
International
Class: |
A61B 1/04 20060101
A61B001/04 |
Claims
1. An apparatus configured to control fluid flow for visualization,
comprising: a barrier projecting distally from a deployment
catheter and defining an open area therein, wherein the open area
is in fluid communication with at least one lumen; at least one
membrane covering the open area and defining at least one aperture
which is sized to control a flow of a clearing fluid infused within
the open area via the at least one lumen; and an imaging element
positioned to image the open area through the clearing fluid.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. patent
application Ser. No. 12/026,455, filed Feb. 5, 2008, which is a
continuation-in-part of U.S. patent application Ser. No. 11/259,498
(now U.S. Pat. No. 7,860,555), which claims the benefit of priority
of U.S. Provisional Application No. 60/888,242 filed Feb. 5, 2007,
each of which is incorporated herein by reference in its
entirety.
FIELD OF THE INVENTION
[0002] The present invention relates generally to medical devices
used for accessing, visualizing, and/or treating regions of tissue
within a body. More particularly, the present invention relates to
flow reduction hood systems for accessing, visualizing, and/or
treating tissue regions with devices that are configured to
facilitate visualization of the tissue.
BACKGROUND OF THE INVENTION
[0003] Conventional devices for accessing and visualizing interior
regions of a body lumen are known. For example, ultrasound devices
have been used to produce images from within a body in vivo.
Ultrasound has been used both with and without contrast agents,
which typically enhance ultrasound-derived images.
[0004] Other conventional methods have utilized catheters or probes
having position sensors deployed within the body lumen, such as the
interior of a cardiac chamber. These types of positional sensors
are typically used to determine the movement of a cardiac tissue
surface or the electrical activity within the cardiac tissue. When
a sufficient number of points have been sampled by the sensors, a
"map" of the cardiac tissue may be generated.
[0005] Another conventional device utilizes an inflatable balloon
which is typically introduced intravascularly in a deflated state
and then inflated against the tissue region to be examined. Imaging
is typically accomplished by an optical fiber or other apparatus
such as electronic chips for viewing the tissue through the
membrane(s) of the inflated balloon. Moreover, the balloon must
generally be inflated for imaging. Other conventional balloons
utilize a cavity or depression formed at a distal end of the
inflated balloon. This cavity or depression is pressed against the
tissue to be examined and is flushed with a clear fluid to provide
a clear pathway through the blood.
[0006] However, such imaging balloons have many inherent
disadvantages. For instance, such balloons generally require that
the balloon be inflated to a relatively large size which may
undesirably displace surrounding tissue and interfere with fine
positioning of the imaging system against the tissue. Moreover, the
working area created by such inflatable balloons are generally
cramped and limited in size. Furthermore, inflated balloons may be
susceptible to pressure changes in the surrounding fluid. For
example, if the environment surrounding the inflated balloon
undergoes pressure changes, e.g., during systolic and diastolic
pressure cycles in a beating heart, the constant pressure change
may affect the inflated balloon volume and its positioning to
produce unsteady or undesirable conditions for optimal tissue
imaging.
[0007] Accordingly, these types of imaging modalities are generally
unable to provide desirable images useful for sufficient diagnosis
and therapy of the endoluminal structure, due in part to factors
such as dynamic forces generated by the natural movement of the
heart. Moreover, anatomic structures within the body can occlude or
obstruct the image acquisition process. Also, the presence and
movement of opaque bodily fluids such as blood generally make in
vivo imaging of tissue regions within the heart difficult.
[0008] Other external imaging modalities are also conventionally
utilized. For example, computed tomography (CT) and magnetic
resonance imaging (MRI) are typical modalities which are widely
used to obtain images of body lumens such as the interior chambers
of the heart. However, such imaging modalities fail to provide
real-time imaging for intra-operative therapeutic procedures.
Fluoroscopic imaging, for instance, is widely used to identify
anatomic landmarks within the heart and other regions of the body.
However, fluoroscopy fails to provide an accurate image of the
tissue quality or surface and also fails to provide for
instrumentation for performing tissue manipulation or other
therapeutic procedures upon the visualized tissue regions. In
addition, fluoroscopy provides a shadow of the intervening tissue
onto a plate or sensor when it may be desirable to view the
intraluminal surface of the tissue to diagnose pathologies or to
perform some form of therapy on it.
[0009] Moreover, many of the conventional imaging systems lack the
capability to provide therapeutic treatments or are difficult to
manipulate in providing effective therapies. For instance, the
treatment in a patient's heart for atrial fibrillation is generally
made difficult by a number of factors, such as visualization of the
target tissue, access to the target tissue, and instrument
articulation and management, amongst others.
[0010] Conventional catheter techniques and devices, for example
such as those described in U.S. Pat. Nos. 5,895,417; 5,941,845; and
6,129,724, used on the epicardial surface of the heart may be
difficult in assuring a transmural lesion or complete blockage of
electrical signals. In addition, current devices may have
difficulty dealing with varying thickness of tissue through which a
transmural lesion desired.
[0011] Conventional accompanying imaging devices, such as
fluoroscopy, are unable to detect perpendicular electrode
orientation, catheter movement during the cardiac cycle, and image
catheter position throughout lesion formation. Without real-time
visualization, it is difficult to reposition devices to another
area that requires transmural lesion ablation. The absence of
real-time visualization also poses the risk of incorrect placement
and ablation of critical structures such as sinus node tissue which
can lead to fatal consequences.
[0012] Thus, a tissue imaging system which is able to provide
real-time in vivo access to and images of tissue regions within
body lumens such as the heart through opaque media such as blood
and which also provides instruments for therapeutic procedures are
desirable.
BRIEF SUMMARY OF THE INVENTION
[0013] The tissue-imaging apparatus described relates to variations
of a device and/or method to provide real-time images in vivo of
tissue regions within a body lumen such as a heart, which is filled
with blood flowing dynamically therethrough. Such an apparatus may
be utilized for many procedures, e.g., mitral valvuloplasty, left
atrial appendage closure, arrhythmia ablation, transseptal access
and patent foramen ovale closure among other procedures. Further
details of such a visualization catheter and methods of use are
shown and described in U.S. Pat. Pub. 2006/0184048 A1, which is
incorporated herein by reference in its entirety.
[0014] A tissue imaging and manipulation apparatus that may be
utilized for procedures within a body lumen, such as the heart, in
which visualization of the surrounding tissue is made difficult, if
not impossible, by medium contained within the lumen such as blood,
is described below. Generally, such a tissue imaging and
manipulation apparatus comprises an optional delivery catheter or
sheath through which a deployment catheter and imaging hood may be
advanced for placement against or adjacent to the tissue to be
imaged.
[0015] The deployment catheter may define a fluid delivery lumen
therethrough as well as an imaging lumen within which an optical
imaging fiber or electronic imaging assembly may be disposed for
imaging tissue. When deployed, the imaging hood may be expanded
into any number of shapes, e.g., cylindrical, conical as shown,
semi-spherical, etc., provided that an open area or field is
defined by the imaging hood. The open area is the area within which
the tissue region of interest may be imaged. The imaging hood may
also define an atraumatic contact lip or edge for placement or
abutment against the tissue region of interest. Moreover, the
distal end of the deployment catheter or separate manipulatable
catheters may be articulated through various controlling mechanisms
such as push-pull wires manually or via computer control
[0016] The visualization catheter may also have one or more
membranes or layers of a polymeric material which covers at least a
portion of the open area. The membrane or layer may be an extension
of the deployed hood or it may be a separate structure. In either
case, the membrane or layer may define at least one opening which
allows for fluid communication between the visualization hood and
the fluid environment within which the catheter is immersed.
[0017] In operation, after the imaging hood has been deployed,
fluid may be pumped at a positive pressure through the fluid
delivery lumen until the fluid fills the open area completely and
displaces any blood from within the open area. When the hood and
membrane or layer is pressed against the tissue region to be
visualized or treated, the contact between the one or more openings
and the tissue surface may help to retain the clear fluid within
the hood for visualization. Moreover, the membrane or layer may
help to retain the fluid within the hood while also minimizing any
fluid leakage therefrom. Additionally, the one or more openings may
also provide for direct access to the underlying tissue region to
be treated by any number of tools or instruments positioned within
the hood.
[0018] The fluid may comprise any biocompatible fluid, e.g.,
saline, water, plasma, Fluorinert.TM., etc., which is sufficiently
transparent to allow for relatively undistorted visualization
through the fluid. The fluid may be pumped continuously or
intermittently to allow for image capture by an optional processor
which may be in communication with the assembly.
[0019] The imaging hood may be deployed into an expanded shape and
retracted within a catheter utilizing various mechanisms. Moreover,
the imaging element, such as a CCD/CMOS imaging camera, may be
positioned distally or proximally of the imaging hood when
collapsed into its low-profile configuration. Such a configuration
may reduce or eliminate friction during deployment and retraction
as well as increase the available space within the catheter not
only for the imaging unit but also for the hood.
[0020] In further controlling the flow of the purging fluid within
the hood, various measures may be taken in configuring the assembly
to allow for the infusion and controlled retention of the clearing
fluid into the hood. By controlling the infusion and retention of
the clearing fluid, the introduction of the clearing fluid into the
patient body may be limited and the clarity of the imaging of the
underlying tissue through the fluid within the hood may be
maintained for relatively longer periods of time by inhibiting,
delaying, or preventing the infusion of surrounding blood into the
viewing field.
[0021] One variation for controlling the flow of the purging fluid
within and from the hood may include a distensible and/or
inflatable membrane which extends over the distal opening of the
hood to at least partially enclose the open area or field with an
aperture defined along the membrane. The aperture may be controlled
to decrease or increase in size via a number of mechanisms to
control the fluid rate therethrough. For instance, the aperture may
be controlled by the inflation or deflation of the membrane
extending over the hood opening. Other variations may utilize a
membrane which is retractable over the hood to control aperture
size.
[0022] Other variations may include aperture openings having other
configurations such as an aperture which is slotted transversely
relative to the catheter. Such a slotted aperture may extend along
the entire length of the diameter of the membrane or just along a
portion thereof to facilitate access of an instrument, e.g.,
ablation instrument, to the underlying visualized tissue. Moreover,
the aperture may also function, e.g., as a template for ablation
probes to create linear ablation lesions on the contacted tissue by
following the slotted aperture as well as restricting or inhibiting
the flow of the purging fluid from the hood. Other variations for
aperture configuration may include one or more slotted openings
which extend in an arcuate or curved manner over the covering or
membrane. Yet another variation may include a meshed membrane or
covering over the distal opening of the hood.
[0023] Other variations for controlling fluid flow may also include
a plurality of inflatable elongate strips or barriers which extend
over the opening of the hood adjacent to one another such that the
entire distal opening of the hood may be closed by inflation or
expansion of these strips or barriers. Yet another variation may
comprise a rotatable barrier which may pivot or rotate relative to
one or more stationary segments which are non-moving relative to
the hood to transition between an open and closed configuration. By
rotating the barrier, segmented openings may be formed between each
respective adjacent segment. By fully rotating the barrier, the
segmented openings may be fully opened and the size of the
segmented openings formed can thus be controlled by rotating the
barrier accordingly.
[0024] In collapsing and/or deploying a hood having a flow-control
aperture, one variation for collapsing such an assembly may include
use of a dilating instrument which may be advanced through the hood
to engage the aperture. As the dilator is pushed further distally,
the support struts supporting the hood may become straightened
relative to the dilator and collapsed into a low-profile
configuration. With this variation, the hood may be collapsed for
delivery without having to retract the hood into a catheter sheath.
Additionally, with the ability to collapse the hood distally rather
than proximally, the projecting tip of the dilator may be used to
actively dilate tissue openings, cavities, flaps, etc. such as the
fossa ovalis or the coronary sinus.
BRIEF DESCRIPTION OF THE DRAWINGS
[0025] FIG. 1A shows a side view of one variation of a tissue
imaging apparatus during deployment from a sheath or delivery
catheter.
[0026] FIG. 1B shows the deployed tissue imaging apparatus of FIG.
1A having an optionally expandable hood or sheath attached to an
imaging and/or diagnostic catheter.
[0027] FIG. 1C shows an end view of a deployed imaging
apparatus.
[0028] FIGS. 1D to 1F show the apparatus of FIGS. 1A to 1C with an
additional lumen, e.g., for passage of a guidewire
therethrough.
[0029] FIGS. 2A and 2B show one example of a deployed tissue imager
positioned against or adjacent to the tissue to be imaged and a
flow of fluid, such as saline, displacing blood from within the
expandable hood.
[0030] FIG. 3A shows an articulatable imaging assembly which may be
manipulated via push-pull wires or by computer control.
[0031] FIGS. 3B and 3C show steerable instruments, respectively,
where an articulatable delivery catheter may be steered within the
imaging hood or a distal portion of the deployment catheter itself
may be steered.
[0032] FIGS. 4A to 4C show side and cross-sectional end views,
respectively, of another variation having an off-axis imaging
capability.
[0033] FIGS. 4D and 4E show examples of various visualization
imagers which may be utilized within or along the imaging hood.
[0034] FIG. 5 shows an illustrative view of an example of a tissue
imager advanced intravascularly within a heart for imaging tissue
regions within an atrial chamber.
[0035] FIGS. 6A to 6C illustrate deployment catheters having one or
more optional inflatable balloons or anchors for stabilizing the
device during a procedure.
[0036] FIGS. 7A and 7B illustrate a variation of an anchoring
mechanism such as a helical tissue piercing device for temporarily
stabilizing the imaging hood relative to a tissue surface.
[0037] FIG. 7C shows another variation for anchoring the imaging
hood having one or more tubular support members integrated with the
imaging hood; each support members may define a lumen therethrough
for advancing a helical tissue anchor within.
[0038] FIG. 8A shows an illustrative example of one variation of
how a tissue imager may be utilized with an imaging device.
[0039] FIG. 8B shows a further illustration of a hand-held
variation of the fluid delivery and tissue manipulation system.
[0040] FIGS. 9A to 9C illustrate an example of capturing several
images of the tissue at multiple regions.
[0041] FIGS. 10A and 10B show charts illustrating how fluid
pressure within the imaging hood may be coordinated with the
surrounding blood pressure; the fluid pressure in the imaging hood
may be coordinated with the blood pressure or it may be regulated
based upon pressure feedback from the blood.
[0042] FIGS. 11A and 11B show perspective and end views,
respectively, of a variation of the tissue visualization catheter
having an aperture defined along the hood which may be narrowed or
closed via an inflatable membrane.
[0043] FIGS. 12A and 12B show perspective and end views,
respectively, of another variation where the aperture size may be
increased upon deflation and/or depressurizing of the inflatable
membrane.
[0044] FIGS. 13A and 13B show perspective and end views,
respectively, of yet another variation where a flow reduction
aperture defined along the hood may be constructed by a distensible
membrane.
[0045] FIGS. 14A and 14B show perspective and end views,
respectively, of variation from of FIG. 13A where the membrane may
be pulled proximally relative to the catheter to expand the
aperture diameter.
[0046] FIGS. 15A and 15B show perspective and end views,
respectively, of another variation where the flow reduction
aperture is defined along the distal end of the hood in a
transverse orientation relative to the catheter longitudinal
axis.
[0047] FIGS. 16A and 16B show perspective and end views,
respectively, of another variation where the flow reduction
aperture is defined along the distal end of the hood in one or more
curved patterns.
[0048] FIGS. 17A and 17B show perspective and end views,
respectively, of another variation having one or more lengths of an
expandable or distensible material defined over the distal
opening.
[0049] FIGS. 18A and 18B show perspective and end views,
respectively, of the variation of FIG. 17A where the one or more
lengths of expandable or distensible material may be inflated or
expanded over the opening of the hood to reduce or restrict flow to
or from the hood.
[0050] FIGS. 19A and 19B show perspective and end views,
respectively, of another variation having one or more slotted
openings which are rotatable relative to the catheter to alter the
size of the openings of the one or more slots.
[0051] FIGS. 20A and 20B show perspective and end views,
respectively, of the variation of FIG. 19A where the one or more
slotted openings may be rotated relative to the catheter into an
open configuration.
[0052] FIG. 21 shows a perspective view of the catheter of FIG. 20A
having the slotted openings rotated into a fully opened
configuration.
[0053] FIGS. 22A and 22B show perspective and end views,
respectively, of yet another variation having a meshed frame over
the distal end of the hood.
[0054] FIGS. 23A to 23D show perspective views of another variation
where a hood may be reduced into its low-profile configuration by
advancing an instrument such as a dilator distally into the hood
and into engagement with the flow reduction aperture to collapse
the hood.
[0055] FIGS. 24A and 24B show side views of the device of FIG. 23A
illustrating engagement of the instrument within the aperture and
the collapse of the hood upon further distal advancement of the
instrument.
DETAILED DESCRIPTION OF THE INVENTION
[0056] A tissue-imaging and manipulation apparatus described below
is able to provide real-time images in vivo of tissue regions
within a body lumen such as a heart, which is filled with blood
flowing dynamically therethrough and is also able to provide
intravascular tools and instruments for performing various
procedures upon the imaged tissue regions. Such an apparatus may be
utilized for many procedures, e.g., facilitating transseptal access
to the left atrium, cannulating the coronary sinus, diagnosis of
valve regurgitation/stenosis, valvuloplasty, atrial appendage
closure, arrhythmogenic focus ablation, among other procedures.
Further examples of tissue visualization catheters which may be
utilized are shown and described in further detail in U.S. patent
application Ser. No. 11/259,498 filed Oct. 25, 2005, which has been
incorporated hereinabove by reference in its entirety.
[0057] One variation of a tissue access and imaging apparatus is
shown in the detail perspective views of FIGS. 1A to 1C. As shown
in FIG. 1A, tissue imaging and manipulation assembly 10 may be
delivered intravascularly through the patient's body in a
low-profile configuration via a delivery catheter or sheath 14. In
the case of treating tissue, such as the mitral valve located at
the outflow tract of the left atrium of the heart, it is generally
desirable to enter or access the left atrium while minimizing
trauma to the patient. To non-operatively effect such access, one
conventional approach involves puncturing the intra-atrial septum
from the right atrial chamber to the left atrial chamber in a
procedure commonly called a transseptal procedure or septostomy.
For procedures such as percutaneous valve repair and replacement,
transseptal access to the left atrial chamber of the heart may
allow for larger devices to be introduced into the venous system
than can generally be introduced percutaneously into the arterial
system.
[0058] When the imaging and manipulation assembly 10 is ready to be
utilized for imaging tissue, imaging hood 12 may be advanced
relative to catheter 14 and deployed from a distal opening of
catheter 14, as shown by the arrow. Upon deployment, imaging hood
12 may be unconstrained to expand or open into a deployed imaging
configuration, as shown in FIG. 1B. Imaging hood 12 may be
fabricated from a variety of pliable or conformable biocompatible
material including but not limited to, e.g., polymeric, plastic, or
woven materials. One example of a woven material is Kevlar.RTM. (E.
I. du Pont de Nemours, Wilmington, Del.), which is an aramid and
which can be made into thin, e.g., less than 0.001 in., materials
which maintain enough integrity for such applications described
herein. Moreover, the imaging hood 12 may be fabricated from a
translucent or opaque material and in a variety of different colors
to optimize or attenuate any reflected lighting from surrounding
fluids or structures, i.e., anatomical or mechanical structures or
instruments. In either case, imaging hood 12 may be fabricated into
a uniform structure or a scaffold-supported structure, in which
case a scaffold made of a shape memory alloy, such as Nitinol, or a
spring steel, or plastic, etc., may be fabricated and covered with
the polymeric, plastic, or woven material. Hence, imaging hood 12
may comprise any of a wide variety of barriers or membrane
structures, as may generally be used to localize displacement of
blood or the like from a selected volume of a body lumen or heart
chamber. In exemplary embodiments, a volume within an inner surface
13 of imaging hood 12 will be significantly less than a volume of
the hood 12 between inner surface 13 and outer surface 11.
[0059] Imaging hood 12 may be attached at interface 24 to a
deployment catheter 16 which may be translated independently of
deployment catheter or sheath 14. Attachment of interface 24 may be
accomplished through any number of conventional methods. Deployment
catheter 16 may define a fluid delivery lumen 18 as well as an
imaging lumen 20 within which an optical imaging fiber or assembly
may be disposed for imaging tissue. When deployed, imaging hood 12
may expand into any number of shapes, e.g., cylindrical, conical as
shown, semi-spherical, etc., provided that an open area or field 26
is defined by imaging hood 12. The open area 26 is the area within
which the tissue region of interest may be imaged. Imaging hood 12
may also define an atraumatic contact lip or edge 22 for placement
or abutment against the tissue region of interest. Moreover, the
diameter of imaging hood 12 at its maximum fully deployed diameter,
e.g., at contact lip or edge 22, is typically greater relative to a
diameter of the deployment catheter 16 (although a diameter of
contact lip or edge 22 may be made to have a smaller or equal
diameter of deployment catheter 16). For instance, the contact edge
diameter may range anywhere from 1 to 5 times (or even greater, as
practicable) a diameter of deployment catheter 16. FIG. 1C shows an
end view of the imaging hood 12 in its deployed configuration. Also
shown are the contact lip or edge 22 and fluid delivery lumen 18
and imaging lumen 20.
[0060] The imaging and manipulation assembly 10 may additionally
define a guidewire lumen therethrough, e.g., a concentric or
eccentric lumen, as shown in the side and end views, respectively,
of FIGS. 1D to 1F. The deployment catheter 16 may define guidewire
lumen 19 for facilitating the passage of the system over or along a
guidewire 17, which may be advanced intravascularly within a body
lumen. The deployment catheter 16 may then be advanced over the
guidewire 17, as generally known in the art.
[0061] In operation, after imaging hood 12 has been deployed, as in
FIG. 1B, and desirably positioned against the tissue region to be
imaged along contact edge 22, the displacing fluid may be pumped at
positive pressure through fluid delivery lumen 18 until the fluid
fills open area 26 completely and displaces any fluid 28 from
within open area 26. The displacing fluid flow may be laminarized
to improve its clearing effect and to help prevent blood from
re-entering the imaging hood 12. Alternatively, fluid flow may be
started before the deployment takes place. The displacing fluid,
also described herein as imaging fluid, may comprise any
biocompatible fluid, e.g., saline, water, plasma, etc., which is
sufficiently transparent to allow for relatively undistorted
visualization through the fluid. Alternatively or additionally, any
number of therapeutic drugs may be suspended within the fluid or
may comprise the fluid itself which is pumped into open area 26 and
which is subsequently passed into and through the heart and the
patient body.
[0062] As seen in the example of FIGS. 2A and 2B, deployment
catheter 16 may be manipulated to position deployed imaging hood 12
against or near the underlying tissue region of interest to be
imaged, in this example a portion of annulus A of mitral valve MV
within the left atrial chamber. As the surrounding blood 30 flows
around imaging hood 12 and within open area 26 defined within
imaging hood 12, as seen in FIG. 2A, the underlying annulus A is
obstructed by the opaque blood 30 and is difficult to view through
the imaging lumen 20. The translucent fluid 28, such as saline, may
then be pumped through fluid delivery lumen 18, intermittently or
continuously, until the blood 30 is at least partially, and
preferably completely, displaced from within open area 26 by fluid
28, as shown in FIG. 2B.
[0063] Although contact edge 22 need not directly contact the
underlying tissue, it is at least preferably brought into close
proximity to the tissue such that the flow of clear fluid 28 from
open area 26 may be maintained to inhibit significant backflow of
blood 30 back into open area 26. Contact edge 22 may also be made
of a soft elastomeric material such as certain soft grades of
silicone or polyurethane, as typically known, to help contact edge
22 conform to an uneven or rough underlying anatomical tissue
surface. Once the blood 30 has been displaced from imaging hood 12,
an image may then be viewed of the underlying tissue through the
clear fluid 30. This image may then be recorded or available for
real-time viewing for performing a therapeutic procedure. The
positive flow of fluid 28 may be maintained continuously to provide
for clear viewing of the underlying tissue. Alternatively, the
fluid 28 may be pumped temporarily or sporadically only until a
clear view of the tissue is available to be imaged and recorded, at
which point the fluid flow 28 may cease and blood 30 may be allowed
to seep or flow back into imaging hood 12. This process may be
repeated a number of times at the same tissue region or at multiple
tissue regions.
[0064] In desirably positioning the assembly at various regions
within the patient body, a number of articulation and manipulation
controls may be utilized. For example, as shown in the
articulatable imaging assembly 40 in FIG. 3A, one or more push-pull
wires 42 may be routed through deployment catheter 16 for steering
the distal end portion of the device in various directions 46 to
desirably position the imaging hood 12 adjacent to a region of
tissue to be visualized. Depending upon the positioning and the
number of push-pull wires 42 utilized, deployment catheter 16 and
imaging hood 12 may be articulated into any number of
configurations 44. The push-pull wire or wires 42 may be
articulated via their proximal ends from outside the patient body
manually utilizing one or more controls. Alternatively, deployment
catheter 16 may be articulated by computer control, as further
described below.
[0065] Additionally or alternatively, an articulatable delivery
catheter 48, which may be articulated via one or more push-pull
wires and having an imaging lumen and one or more working lumens,
may be delivered through the deployment catheter 16 and into
imaging hood 12. With a distal portion of articulatable delivery
catheter 48 within imaging hood 12, the clear displacing fluid may
be pumped through delivery catheter 48 or deployment catheter 16 to
clear the field within imaging hood 12. As shown in FIG. 3B, the
articulatable delivery catheter 48 may be articulated within the
imaging hood to obtain a better image of tissue adjacent to the
imaging hood 12. Moreover, articulatable delivery catheter 48 may
be articulated to direct an instrument or tool passed through the
catheter 48, as described in detail below, to specific areas of
tissue imaged through imaging hood 12 without having to reposition
deployment catheter 16 and re-clear the imaging field within hood
12.
[0066] Alternatively, rather than passing an articulatable delivery
catheter 48 through the deployment catheter 16, a distal portion of
the deployment catheter 16 itself may comprise a distal end 49
which is articulatable within imaging hood 12, as shown in FIG. 3C.
Directed imaging, instrument delivery, etc., may be accomplished
directly through one or more lumens within deployment catheter 16
to specific regions of the underlying tissue imaged within imaging
hood 12.
[0067] Visualization within the imaging hood 12 may be accomplished
through an imaging lumen 20 defined through deployment catheter 16,
as described above. In such a configuration, visualization is
available in a straight-line manner, i.e., images are generated
from the field distally along a longitudinal axis defined by the
deployment catheter 16. Alternatively or additionally, an
articulatable imaging assembly having a pivotable support member 50
may be connected to, mounted to, or otherwise passed through
deployment catheter 16 to provide for visualization off-axis
relative to the longitudinal axis defined by deployment catheter
16, as shown in FIG. 4A. Support member 50 may have an imaging
element 52, e.g., a CCD or CMOS imager or optical fiber, attached
at its distal end with its proximal end connected to deployment
catheter 16 via a pivoting connection 54.
[0068] If one or more optical fibers are utilized for imaging, the
optical fibers 58 may be passed through deployment catheter 16, as
shown in the cross-section of FIG. 4B, and routed through the
support member 50. The use of optical fibers 58 may provide for
increased diameter sizes of the one or several lumens 56 through
deployment catheter 16 for the passage of diagnostic and/or
therapeutic tools therethrough. Alternatively, electronic chips,
such as a charge coupled device (CCD) or a CMOS imager, which are
typically known, may be utilized in place of the optical fibers 58,
in which case the electronic imager may be positioned in the distal
portion of the deployment catheter 16 with electric wires being
routed proximally through the deployment catheter 16.
Alternatively, the electronic imagers may be wirelessly coupled to
a receiver for the wireless transmission of images. Additional
optical fibers or light emitting diodes (LEDs) can be used to
provide lighting for the image or operative theater, as described
below in further detail. Support member 50 may be pivoted via
connection 54 such that the member 50 can be positioned in a
low-profile configuration within channel or groove 60 defined in a
distal portion of catheter 16, as shown in the cross-section of
FIG. 4C. During intravascular delivery of deployment catheter 16
through the patient body, support member 50 can be positioned
within channel or groove 60 with imaging hood 12 also in its
low-profile configuration. During visualization, imaging hood 12
may be expanded into its deployed configuration and support member
50 may be deployed into its off-axis configuration for imaging the
tissue adjacent to hood 12, as in FIG. 4A. Other configurations for
support member 50 for off-axis visualization may be utilized, as
desired.
[0069] FIG. 4D shows a partial cross-sectional view of an example
where one or more optical fiber bundles 62 may be positioned within
the catheter and within imaging hood 12 to provide direct in-line
imaging of the open area within hood 12. FIG. 4E shows another
example where an imaging element 64 (e.g., CCD or CMOS electronic
imager) may be placed along an interior surface of imaging hood 12
to provide imaging of the open area such that the imaging element
64 is off-axis relative to a longitudinal axis of the hood 12. The
off-axis position of element 64 may provide for direct
visualization and uninhibited access by instruments from the
catheter to the underlying tissue during treatment.
[0070] FIG. 5 shows an illustrative cross-sectional view of a heart
H having tissue regions of interest being viewed via an imaging
assembly 10. In this example, delivery catheter assembly 70 may be
introduced percutaneously into the patient's vasculature and
advanced through the superior vena cava SVC and into the right
atrium RA. The delivery catheter or sheath 72 may be articulated
through the atrial septum AS and into the left atrium LA for
viewing or treating the tissue, e.g., the annulus A, surrounding
the mitral valve MV. As shown, deployment catheter 16 and imaging
hood 12 may be advanced out of delivery catheter 72 and brought
into contact or in proximity to the tissue region of interest. In
other examples, delivery catheter assembly 70 may be advanced
through the inferior vena cava IVC, if so desired. Moreover, other
regions of the heart H, e.g., the right ventricle RV or left
ventricle LV, may also be accessed and imaged or treated by imaging
assembly 10.
[0071] In accessing regions of the heart H or other parts of the
body, the delivery catheter or sheath 14 may comprise a
conventional intra-vascular catheter or an endoluminal delivery
device. Alternatively, robotically-controlled delivery catheters
may also be optionally utilized with the imaging assembly described
herein, in which case a computer-controller 74 may be used to
control the articulation and positioning of the delivery catheter
14. An example of a robotically-controlled delivery catheter which
may be utilized is described in further detail in US Pat. Pub.
2002/0087169 A1 to Brock et al. entitled "Flexible Instrument",
which is incorporated herein by reference in its entirety. Other
robotically-controlled delivery catheters manufactured by Hansen
Medical, Inc. (Mountain View, Calif.) may also be utilized with the
delivery catheter 14.
[0072] To facilitate stabilization of the deployment catheter 16
during a procedure, one or more inflatable balloons or anchors 76
may be positioned along the length of catheter 16, as shown in FIG.
6A. For example, when utilizing a transseptal approach across the
atrial septum AS into the left atrium LA, the inflatable balloons
76 may be inflated from a low-profile into their expanded
configuration to temporarily anchor or stabilize the catheter 16
position relative to the heart H. FIG. 6B shows a first balloon 78
inflated while FIG. 6C also shows a second balloon 80 inflated
proximal to the first balloon 78. In such a configuration, the
septal wall AS may be wedged or sandwiched between the balloons 78,
80 to temporarily stabilize the catheter 16 and imaging hood 12. A
single balloon 78 or both balloons 78, 80 may be used. Other
alternatives may utilize expandable mesh members, malecots, or any
other temporary expandable structure. After a procedure has been
accomplished, the balloon assembly 76 may be deflated or
re-configured into a low-profile for removal of the deployment
catheter 16.
[0073] To further stabilize a position of the imaging hood 12
relative to a tissue surface to be imaged, various anchoring
mechanisms may be optionally employed for temporarily holding the
imaging hood 12 against the tissue. Such anchoring mechanisms may
be particularly useful for imaging tissue which is subject to
movement, e.g., when imaging tissue within the chambers of a
beating heart. A tool delivery catheter 82 having at least one
instrument lumen and an optional visualization lumen may be
delivered through deployment catheter 16 and into an expanded
imaging hood 12. As the imaging hood 12 is brought into contact
against a tissue surface T to be examined, anchoring mechanisms
such as a helical tissue piercing device 84 may be passed through
the tool delivery catheter 82, as shown in FIG. 7A, and into
imaging hood 12.
[0074] The helical tissue engaging device 84 may be torqued from
its proximal end outside the patient body to temporarily anchor
itself into the underlying tissue surface T. Once embedded within
the tissue T, the helical tissue engaging device 84 may be pulled
proximally relative to deployment catheter 16 while the deployment
catheter 16 and imaging hood 12 are pushed distally, as indicated
by the arrows in FIG. 7B, to gently force the contact edge or lip
22 of imaging hood against the tissue T. The positioning of the
tissue engaging device 84 may be locked temporarily relative to the
deployment catheter 16 to ensure secure positioning of the imaging
hood 12 during a diagnostic or therapeutic procedure within the
imaging hood 12. After a procedure, tissue engaging device 84 may
be disengaged from the tissue by torquing its proximal end in the
opposite direction to remove the anchor form the tissue T and the
deployment catheter 16 may be repositioned to another region of
tissue where the anchoring process may be repeated or removed from
the patient body. The tissue engaging device 84 may also be
constructed from other known tissue engaging devices such as
vacuum-assisted engagement or grasper-assisted engagement tools,
among others.
[0075] Although a helical anchor 84 is shown, this is intended to
be illustrative and other types of temporary anchors may be
utilized, e.g., hooked or barbed anchors, graspers, etc. Moreover,
the tool delivery catheter 82 may be omitted entirely and the
anchoring device may be delivered directly through a lumen defined
through the deployment catheter 16.
[0076] In another variation where the tool delivery catheter 82 may
be omitted entirely to temporarily anchor imaging hood 12, FIG. 7C
shows an imaging hood 12 having one or more tubular support members
86, e.g., four support members 86 as shown, integrated with the
imaging hood 12. The tubular support members 86 may define lumens
therethrough each having helical tissue engaging devices 88
positioned within. When an expanded imaging hood 12 is to be
temporarily anchored to the tissue, the helical tissue engaging
devices 88 may be urged distally to extend from imaging hood 12 and
each may be torqued from its proximal end to engage the underlying
tissue T. Each of the helical tissue engaging devices 88 may be
advanced through the length of deployment catheter 16 or they may
be positioned within tubular support members 86 during the delivery
and deployment of imaging hood 12. Once the procedure within
imaging hood 12 is finished, each of the tissue engaging devices 88
may be disengaged from the tissue and the imaging hood 12 may be
repositioned to another region of tissue or removed from the
patient body.
[0077] An illustrative example is shown in FIG. 8A of a tissue
imaging assembly connected to a fluid delivery system 90 and to an
optional processor 98 and image recorder and/or viewer 100. The
fluid delivery system 90 may generally comprise a pump 92 and an
optional valve 94 for controlling the flow rate of the fluid into
the system. A fluid reservoir 96, fluidly connected to pump 92, may
hold the fluid to be pumped through imaging hood 12. An optional
central processing unit or processor 98 may be in electrical
communication with fluid delivery system 90 for controlling flow
parameters such as the flow rate and/or velocity of the pumped
fluid. The processor 98 may also be in electrical communication
with an image recorder and/or viewer 100 for directly viewing the
images of tissue received from within imaging hood 12. Imager
recorder and/or viewer 100 may also be used not only to record the
image but also the location of the viewed tissue region, if so
desired.
[0078] Optionally, processor 98 may also be utilized to coordinate
the fluid flow and the image capture. For instance, processor 98
may be programmed to provide for fluid flow from reservoir 96 until
the tissue area has been displaced of blood to obtain a clear
image. Once the image has been determined to be sufficiently clear,
either visually by a practitioner or by computer, an image of the
tissue may be captured automatically by recorder 100 and pump 92
may be automatically stopped or slowed by processor 98 to cease the
fluid flow into the patient. Other variations for fluid delivery
and image capture are, of course, possible and the aforementioned
configuration is intended only to be illustrative and not
limiting.
[0079] FIG. 8B shows a further illustration of a hand-held
variation of the fluid delivery and tissue manipulation system 110.
In this variation, system 110 may have a housing or handle assembly
112 which can be held or manipulated by the physician from outside
the patient body. The fluid reservoir 114, shown in this variation
as a syringe, can be fluidly coupled to the handle assembly 112 and
actuated via a pumping mechanism 116, e.g., lead screw. Fluid
reservoir 114 may be a simple reservoir separated from the handle
assembly 112 and fluidly coupled to handle assembly 112 via one or
more tubes. The fluid flow rate and other mechanisms may be metered
by the electronic controller 118.
[0080] Deployment of imaging hood 12 may be actuated by a hood
deployment switch 120 located on the handle assembly 112 while
dispensation of the fluid from reservoir 114 may be actuated by a
fluid deployment switch 122, which can be electrically coupled to
the controller 118. Controller 118 may also be electrically coupled
to a wired or wireless antenna 124 optionally integrated with the
handle assembly 112, as shown in the figure. The wireless antenna
124 can be used to wirelessly transmit images captured from the
imaging hood 12 to a receiver, e.g., via Bluetooth.RTM. wireless
technology (Bluetooth SIG, Inc., Bellevue, Wash.), RF, etc., for
viewing on a monitor 128 or for recording for later viewing.
[0081] Articulation control of the deployment catheter 16, or a
delivery catheter or sheath 14 through which the deployment
catheter 16 may be delivered, may be accomplished by computer
control, as described above, in which case an additional controller
may be utilized with handle assembly 112. In the case of manual
articulation, handle assembly 112 may incorporate one or more
articulation controls 126 for manual manipulation of the position
of deployment catheter 16. Handle assembly 112 may also define one
or more instrument ports 130 through which a number of
intravascular tools may be passed for tissue manipulation and
treatment within imaging hood 12, as described further below.
Furthermore, in certain procedures, fluid or debris may be sucked
into imaging hood 12 for evacuation from the patient body by
optionally fluidly coupling a suction pump 132 to handle assembly
112 or directly to deployment catheter 16.
[0082] As described above, fluid may be pumped continuously into
imaging hood 12 to provide for clear viewing of the underlying
tissue. Alternatively, fluid may be pumped temporarily or
sporadically only until a clear view of the tissue is available to
be imaged and recorded, at which point the fluid flow may cease and
the blood may be allowed to seep or flow back into imaging hood 12.
FIGS. 9A to 9C illustrate an example of capturing several images of
the tissue at multiple regions. Deployment catheter 16 may be
desirably positioned and imaging hood 12 deployed and brought into
position against a region of tissue to be imaged, in this example
the tissue surrounding a mitral valve MV within the left atrium of
a patient's heart. The imaging hood 12 may be optionally anchored
to the tissue, as described above, and then cleared by pumping the
imaging fluid into the hood 12. Once sufficiently clear, the tissue
may be visualized and the image captured by control electronics
118. The first captured image 140 may be stored and/or transmitted
wirelessly 124 to a monitor 128 for viewing by the physician, as
shown in FIG. 9A.
[0083] The deployment catheter 16 may be then repositioned to an
adjacent portion of mitral valve MV, as shown in FIG. 9B, where the
process may be repeated to capture a second image 142 for viewing
and/or recording. The deployment catheter 16 may again be
repositioned to another region of tissue, as shown in FIG. 9C,
where a third image 144 may be captured for viewing and/or
recording. This procedure may be repeated as many times as
necessary for capturing a comprehensive image of the tissue
surrounding mitral valve MV, or any other tissue region. When the
deployment catheter 16 and imaging hood 12 is repositioned from
tissue region to tissue region, the pump may be stopped during
positioning and blood or surrounding fluid may be allowed to enter
within imaging hood 12 until the tissue is to be imaged, where the
imaging hood 12 may be cleared, as above.
[0084] As mentioned above, when the imaging hood 12 is cleared by
pumping the imaging fluid within for clearing the blood or other
bodily fluid, the fluid may be pumped continuously to maintain the
imaging fluid within the hood 12 at a positive pressure or it may
be pumped under computer control for slowing or stopping the fluid
flow into the hood 12 upon detection of various parameters or until
a clear image of the underlying tissue is obtained. The control
electronics 118 may also be programmed to coordinate the fluid flow
into the imaging hood 12 with various physical parameters to
maintain a clear image within imaging hood 12.
[0085] One example is shown in FIG. 10A which shows a chart 150
illustrating how fluid pressure within the imaging hood 12 may be
coordinated with the surrounding blood pressure. Chart 150 shows
the cyclical blood pressure 156 alternating between diastolic
pressure 152 and systolic pressure 154 over time T due to the
beating motion of the patient heart. The fluid pressure of the
imaging fluid, indicated by plot 160, within imaging hood 12 may be
automatically timed to correspond to the blood pressure changes 160
such that an increased pressure is maintained within imaging hood
12 which is consistently above the blood pressure 156 by a slight
increase .DELTA.P, as illustrated by the pressure difference at the
peak systolic pressure 158. This pressure difference, .DELTA.P, may
be maintained within imaging hood 12 over the pressure variance of
the surrounding blood pressure to maintain a positive imaging fluid
pressure within imaging hood 12 to maintain a clear view of the
underlying tissue. One benefit of maintaining a constant .DELTA.P
is a constant flow and maintenance of a clear field.
[0086] FIG. 10B shows a chart 162 illustrating another variation
for maintaining a clear view of the underlying tissue where one or
more sensors within the imaging hood 12, as described in further
detail below, may be configured to sense pressure changes within
the imaging hood 12 and to correspondingly increase the imaging
fluid pressure within imaging hood 12. This may result in a time
delay, .DELTA.T, as illustrated by the shifted fluid pressure 160
relative to the cycling blood pressure 156, although the time
delays .DELTA.T may be negligible in maintaining the clear image of
the underlying tissue. Predictive software algorithms can also be
used to substantially eliminate this time delay by predicting when
the next pressure wave peak will arrive and by increasing the
pressure ahead of the pressure wave's arrival by an amount of time
equal to the aforementioned time delay to essentially cancel the
time delay out.
[0087] The variations in fluid pressure within imaging hood 12 may
be accomplished in part due to the nature of imaging hood 12. An
inflatable balloon, which is conventionally utilized for imaging
tissue, may be affected by the surrounding blood pressure changes.
On the other hand, an imaging hood 12 retains a constant volume
therewithin and is structurally unaffected by the surrounding blood
pressure changes, thus allowing for pressure increases therewithin.
The material that hood 12 is made from may also contribute to the
manner in which the pressure is modulated within this hood 12. A
stiffer hood material, such as high durometer polyurethane or
Nylon, may facilitate the maintaining of an open hood when
deployed. On the other hand, a relatively lower durometer or softer
material, such as a low durometer PVC or polyurethane, may collapse
from the surrounding fluid pressure and may not adequately maintain
a deployed or expanded hood.
[0088] In further controlling the flow of the purging fluid within
the hood 12, various measures may be taken in configuring the
assembly to allow for the infusion and controlled retention of the
clearing fluid into the hood. By controlling the infusion and
retention of the clearing fluid, the introduction of the clearing
fluid into the patient body may be limited and the clarity of the
imaging of the underlying tissue through the fluid within the hood
12 may be maintained for relatively longer periods of time by
inhibiting, delaying, or preventing the infusion of surrounding
blood into the viewing field.
[0089] As shown in the perspective and end views of FIGS. 11A and
11B, respectively, one variation for controlling the flow of the
purging fluid within and from hood 12 may include a distensible
and/or inflatable membrane 170 which extends over the distal
opening of hood 12 to at least partially enclose open area or field
26. A variably-sized aperture 172 may be defined over membrane 170
such that aperture 172 is relatively in-line with deployment
catheter 16 such that instruments may be passed directly through
aperture 172. Alternatively, aperture 172 may be positioned at
other regions over membrane 170, if so desired.
[0090] Membrane 170 may be comprised of the same or similar
material as the rest of hood 12 or some other elastomeric material
which is relatively transparent to allow for viewing through
membrane 170 of underlying tissue to be imaged. Moreover, membrane
170 may be comprised of a dual-layer to trap a transparent fluid or
gas which may be infused between the layers such that aperture 172
may be forced to contract or reduce in diameter, as shown in FIG.
11B, as indicated by the direction of aperture restriction 174.
Imager 176, e.g., CCD, CMOS, etc., is shown in an off-axis position
along hood 12 relative to a longitudinal axis of the deployment
catheter 16 for imaging the visualized tissue within hood 12. To
enlarge aperture 172, the fluid or gas within membrane 170 may be
deflated or depressurized such that aperture 172 is enlarged, as
indicated by the direction of aperture expansion 178 in the
perspective and end views of FIGS. 12A and 12B, respectively. In
this manner, the size of aperture 172 may be controllable in real
time to range anywhere from completely closing upon itself to seal
the interior of hood 12 from the surrounding environment to opening
completely to the circumference of hood 12 depending upon the size
of aperture 172 to be implemented. Moreover, although aperture 172
is illustrated to be circular, other shapes may be implemented as
well, e.g., elliptical, triangular, rectangular, etc., as so
desired.
[0091] In use, with membrane 170 of hood 12 positioned against a
tissue region of interest such as within the heart of the patient,
saline or other transparent fluids may be infused within hood 12
such that the hood interior is cleared of any blood or other opaque
bodily fluids. The purged blood and fluids may exit from aperture
172 and into the surrounding environment such that a clear field of
view remains for imaging through the interior of hood 12 and/or
through membrane 170 upon the underlying tissue. Membrane 170 may
be infused with the gas or fluid to reduce the diameter of aperture
172. In this manner, aperture 172 may be simply reduced in size,
e.g., 1 to 4 mm in diameter, to restrict or reduce the escape of
the purging fluid from hood 12 while also restricting or reducing
the in-flow of blood back into hood 12 or aperture 172 may be
completely sealed shut to retain the purging fluid within. Because
membrane 170 is fabricated from a clear or transparent material and
the infused gas or fluid is also clear, visualization of the tissue
through the membrane 170 may be accomplished unobstructed. Aperture
172 may also be expanded to various diameters to allow for the
passage of any number of instruments from catheter 16 for use upon
the underlying tissue in any number of procedures.
[0092] FIGS. 13A and 13B illustrate another variation of a flow
reduction aperture that is variable in size in the perspective and
end views, respectively. In this variation, a transparent
distensible membrane 180 may be positioned or stretched over a
scaffold or frame to form hood 12. Membrane 180 may further extend
over atraumatic contact lip or edge 22 to form a covering over the
distal opening of hood 12. Aperture 182 may be defined along
membrane 180 to form an aperture, e.g., 1 to 4 mm in diameter, for
use in visualizing tissue regions. The size of aperture 182 may be
varied, e.g., by pulling membrane 180 proximally, as indicated by
the direction of membrane withdrawal 184 in the perspective view of
FIG. 14A, relative to hood 12 via a retraction mechanism such as
pull wires or tensioning members embedded in the catheter. As the
membrane is distensible, retraction 184 of membrane 180 may expand
aperture 182, as indicated by the direction of aperture expansion
186 in the end view of FIG. 14B to allow for the passage of any
number of instruments into and/or through hood 12. Because of the
distensible nature of membrane 180, release of the membrane may
allow aperture 182 to naturally retract into a smaller opening.
Aperture 182 may be sized in use at any time during a procedure, as
described above.
[0093] Aside from variably sized apertures, openings having other
configurations may be utilized to control, restrict, or inhibit the
flow of fluids from or through the hood. An example is illustrated
in the perspective and end views of FIGS. 15A and 15B,
respectively, which shows hood 12 having a transparent covering or
membrane 190, as above, but defining an aperture 192 which is
slotted transversely relative to catheter 16. Slotted aperture 192
may extend along the entire length of the diameter of membrane 190
or just along a portion thereof to facilitate access of an
instrument 194, e.g., ablation instrument, to the underlying
visualized tissue. Moreover, aperture 192 may also function, e.g.,
as a template for ablation probes to create linear ablation lesions
on the contacted tissue by following the slotted aperture 192 as
well as restricting or inhibiting the flow of the purging fluid
from hood 12.
[0094] Another variation of an aperture which is configured into a
shape is illustrated in the perspective and end views of FIGS. 16A
and 16B, respectively. In this particular variation, one or more
slotted openings may form curved apertures 202, 204 which extend in
an arcuate or curved manner over covering or membrane 200. Although
two symmetric apertures 202, 204 are illustrated, a single curved
aperture may be utilized or several curved apertures which extend
circumferentially in uniform or non-uniform discrete sections may
also be utilized. As above, these curved apertures 202, 204 may be
utilized as a template for the creation of curved lesions upon the
underlying tissue while also restricting or inhibiting the flow of
the purging fluid from hood 12. Moreover, this or any of the other
variations may be constructed either with an inflatable
double-layered distensible membrane or with a single-layered
membrane.
[0095] In yet another variation, FIGS. 17A and 17B illustrate
perspective and end views, respectively, of a hood 12 which may
utilize a plurality of inflatable elongate strips or barriers 210
which extend over the opening of hood 12 adjacent to one another
such that the entire distal opening of hood 12 may be closed by
inflation or expansion of these strips or barriers 210. These
strips or barriers may be comprised of a transparent elastomeric
material such as silicon, polyurethane, latex, etc. each having a
width ranging from, e.g., 2 to 3 mm, and which are each attached at
opposing ends of hood 12. In their non-inflated state, strips or
barriers 210 may form a number of openings 212 between each strip
through which an instrument 194 may be passed through. Once hood 12
has been purged of blood, each strip or barrier 210 may be inflated
at least partially to close the openings 212 and to restrict the
flow of purging fluid from hood 12 and the flow of blood back into
hood 12. Alternatively, strips or barriers 210 may be fully
inflated or expanded such that each strip or barrier 210 forms an
overlapping portion 214 with an adjacent strip or barrier 210 to
fully prevent or inhibit fluid exchange between the hood interior
and the surrounding bodily fluids while maintaining visualization
of the underlying tissue through the inflated or elongated strips
or barriers 210, as shown in the perspective and end views of FIGS.
18A and 18B, respectively. Moreover, the strips or barriers 210 and
hood 12 can share the same fluid or gas lining to simultaneously
perform inflation or deflation operations during the purging
process.
[0096] The purging fluid can be irrigated out of hood 12 when
additional purging fluid is injected, consequently increasing fluid
pressure within hood 12 to force the fluid through the overlapping
gaps 214 of the strips or barriers 210. As described above, any
number of therapeutic instruments 194 (e.g., ablation probes,
guidewires, needles, graspers, dilators, etc.) can be deployed out
of hood 12 through openings 212. In addition, instruments 194 are
able to navigate linearly along and through these openings 212 to
facilitate operations such as the formation of linear tissue
lesions for atrial or ventricular fibrillation, etc.
[0097] In yet another variation, FIGS. 19A and 19B illustrate
perspective and end views, respectively, of hood 12 which comprises
a rotatable barrier 220 which may pivot or rotate relative to one
or more stationary segments 230, 232, 234 which are non-moving
relative to hood 12 to transition between an open and closed
configuration. Rotatable barrier 220 may be formed by one or more
rotatable segments 224, 226, 228 which are spaced, uniformly or
non-uniformly, apart from one another and each joined at a common
pivot or rotational point 222 located near or at the center of hood
12. The stationary segments 230, 232, 234 may also be spaced from
one another in a complementary manner relative to rotatable
segments 224, 226, 228 and each may be connected to hood 12 around
the periphery of lip or edge 22 such that when each of the segments
of both the rotatable barrier 220 and the stationary segments are
aligned adjacent to one another, the interior of hood 12 may be
sealed to retain the purging fluid within.
[0098] By rotating the barrier 220 about pivot 222, e.g.,
counterclockwise as indicated by the direction of rotation 246 or
clockwise relative to stationary segments 230, 232, 234 and the
longitudinal axis of hood 12, segmented openings 240, 242, 244 may
be formed between each respective adjacent segment, as shown in the
perspective and end views of FIGS. 20A and 20B. By fully rotating
barrier 220, segmented openings 240, 242, 244 may be fully opened,
as shown in the perspective view of FIG. 21. The size of the
segmented openings 240, 242, 244 formed can thus be controlled by
rotating barrier 220 accordingly. Irrigation and/or deployment of
instruments through hood 12 can be made through these formed
segmented openings 240, 242, 244. Hood 12 can be used for
visualization and therapeutic procedures with barrier 220 in either
its fully closed or fully opened configuration or any size opening
formed.
[0099] Another variation is illustrated in the perspective and end
views of FIGS. 22A and 22B, respectively, where hood 12 may include
a mesh frame 250 fabricated from a transparent polymeric material
such as PVC, polyurethane, PET, etc. which covers the opening of
hood 12 to restrict or reduce the flow of fluid from and into hood
12. The plurality of distributed openings 252 across mesh frame 250
may allow for the purging fluid to be evenly irrigated out of hood
12 as compared to a single relatively larger aperture. Any number
of therapeutic instruments as described above can be deployed by
passing them through the openings 252 in the mesh frame 250.
Moreover, the size of openings 252 may be varied depending upon the
size of the instruments to be used as well as the desired overall
area to be imaged.
[0100] FIGS. 23A to 23D illustrate perspective views of yet another
variation of a hood assembly covered by a membrane 260 and which
defines an aperture 262 having a diameter of, e.g., 1 to 4 mm, over
membrane 260 at a distal end of hood 12. This variation in
particular shows an example of an assembly which is configured to
restrict or control fluid flow into and out of hood 12 and which is
also collapsible into a low-profile configuration which is
utilizable as a tissue dilator.
[0101] As shown, hood 12 may be defined by several support struts
264 made from materials such as Nitinol, nylon, Mylar, etc., which
extend from the proximal end of hood 12 and define curved or bent
portions 266 which terminate at the distal end of hood 12 at the
flow control aperture 262. A strut may also form a ring surrounding
aperture 262 to provide circumferential strength to aperture 262,
as shown in FIG. 23A. In its deployed configuration, hood 12 with
aperture 262 may be utilized to visualize and/or treat tissue while
restricting or controlling the flow of fluid from and into hood 12
via aperture 262. To deploy and/or collapse hood 12 between its
deployed and low-profile configurations, an instrument 268 such as
a dilator having an atraumatic tip 270 projecting distally from a
shoulder 272 may be advanced distally through the deployment
catheter and into hood 12, as shown in FIG. 23B.
[0102] Instrument 268 may be further advanced until tip 270
projects through aperture 262 and shoulder 272 engages or abuts
against the interior of membrane 260 surrounding aperture 262. As
instrument 268 is pushed further distally, the curved or bent
portions 266 of support struts 264 may become start to become
straightened relative to instrument 268 and support struts 264 may
begin to collapse, as shown in FIG. 23C. Once instrument 268 has
been fully advanced into its distal position, portions 266 and
support struts 264 may be fully collapsed against instrument 268
into a low-profile configuration, as shown in FIG. 23D. FIGS. 24A
and 24B illustrate side views of support struts 264 collapsing and
portions 266 extending into their straightened configurations
against instrument 268.
[0103] With this variation, hood 12 may be collapsed for delivery
without having to retract hood 12 into a catheter sheath 14.
Additionally, with the ability to collapse hood 12 distally rather
than proximally, projecting tip 270 may be used to actively dilate
tissue openings, cavities, flaps, etc. such as the fossa ovalis or
the coronary sinus. With direct dilation, hood 12 may be guided to
pass through the tissue opening, cavity, or flap in a single
process. Procedures such as transseptal access or coronary sinus
cannulation can therefore be performed more efficiently.
[0104] The applications of the disclosed invention discussed above
are not limited to certain treatments or regions of the body, but
may include any number of other treatments and areas of the body.
Modification of the above-described methods and devices for
carrying out the invention, and variations of aspects of the
invention that are obvious to those of skill in the arts are
intended to be within the scope of this disclosure. Moreover,
various combinations of aspects between examples are also
contemplated and are considered to be within the scope of this
disclosure as well.
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